412 lines
15 KiB
Markdown
412 lines
15 KiB
Markdown
# convention 4 kubernetes: c4k-common
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[](https://clojars.org/org.domaindrivenarchitecture/c4k-common-clj) [](https://clojars.org/org.domaindrivenarchitecture/c4k-common-cljs) [](https://gitlab.com/domaindrivenarchitecture/c4k-common/-/commits/master)
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[<img src="https://domaindrivenarchitecture.org/img/delta-chat.svg" width=20 alt="DeltaChat"> chat over e-mail](mailto:buero@meissa-gmbh.de?subject=community-chat) | [<img src="https://meissa-gmbh.de/img/community/Mastodon_Logotype.svg" width=20 alt="team@social.meissa-gmbh.de"> team@social.meissa-gmbh.de](https://social.meissa-gmbh.de/@team) | [Website & Blog](https://domaindrivenarchitecture.org)
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## Rationale
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There are many comparable solutions for creating c4k deployments like `helm` or `kustomize`.
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`kustomize` is great to manage your k8s manifests by splitting huge files into handy parts.
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`helm` is great because of its large community.
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Why do we need another one? Why do you continue the reading here?
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We combine the simplicity of `kustomize` with the ability to do real programming like software developers would do.
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Following the principle
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"Use programming language for programming"
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we clearly enjoy writing Kubernetes manifests with Clojure. In comparison to helms templating, things such as business logic, conventions, input validation, versions, dependencies and reuse are much easier and much more reliable to implement with c4k.
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By the way, c4k means "convention for kubernetes".
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### Features
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c4k-common supports the following use cases:
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- [convention 4 kubernetes: c4k-common](#convention-4-kubernetes-c4k-common)
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- [Rationale](#rationale)
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- [Features](#features)
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- [Target CLI and Web Frontend](#target-cli-and-web-frontend)
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- [Separate Configuration From Credentials](#separate-configuration-from-credentials)
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- [Input as EDN or Yaml](#input-as-edn-or-yaml)
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- [Inline k8s Resources for Versioning \& Dependencies](#inline-k8s-resources-for-versioning--dependencies)
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- [Work on Structured Data Instead of Flat Templating](#work-on-structured-data-instead-of-flat-templating)
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- [Validate Your Inputs](#validate-your-inputs)
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- [Namespaces](#namespaces)
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- [Ingress](#ingress)
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- [Postgres Database](#postgres-database)
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- [Monitoring With Grafana Cloud](#monitoring-with-grafana-cloud)
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- [Refactoring \& Module Overview](#refactoring--module-overview)
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- [Development \& Mirrors](#development--mirrors)
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- [License](#license)
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#### Target CLI and Web Frontend
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To create your own c4k module set up your cli analogous to the following:
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```clojure
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(defn -main [& cmd-args]
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(uberjar/main-common
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"c4k-forgejo" ;; name of your app
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core/config? ;; schema for config validation
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core/auth? ;; schema for credential validation
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core/config-defaults ;; want to set default values?
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core/k8s-objects ;; the function generate the k8s manifest
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cmd-args ;; command line arguments given
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))
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```
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The full example can be found here: https://repo.prod.meissa.de/meissa/c4k-forgejo/src/branch/main/src/main/clj/dda/c4k_forgejo/uberjar.clj
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With c4k instead of using cli to generate manifests, you can also generate your manifests via web-application (using page local js without server interaction)
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```html
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<html>
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<head>
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<link href="bootstrap.min.css" rel="stylesheet" type="text/css" />
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</head>
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<body>
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<div id="c4k-content"></div>
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<script src="js/main.js"></script>
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</body>
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</html>
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```
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[](https://domaindrivenarchitecture.org/pages/dda-provision/c4k-forgejo/)
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See: https://repo.prod.meissa.de/meissa/c4k-forgejo/src/branch/main/public/index.html
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and: https://repo.prod.meissa.de/meissa/c4k-forgejo/src/branch/main/src/main/cljs/dda/c4k_forgejo/browser.cljs
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#### Separate Configuration From Credentials
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We think it is a good idea to have credentials separated from configuration. All our functions, cli and frontend are following this principle. Thus, for executing separated config and authentication infos have to be provided.
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The following command line yields the resulting k8s manifests in `k8s-manifest.yaml`:
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```bash
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java -jar c4k-common.jar config.edn auth.edn > k8s-manifest.yaml
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```
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Using the tool `jarwrapper` the command line can even be shortened to:
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```bash
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c4k-common config.edn auth.edn > k8s-manifest.yaml
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```
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#### Input as EDN or Yaml
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c4k-common supports yaml and edn as format for all of its resources (input and output).
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Hence, the following command line will also work:
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```bash
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c4k-common config.yaml auth.yaml > k8s-manifest.yaml
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```
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#### Inline k8s Resources for Versioning & Dependencies
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We inline all resources used in our libraries & applications. You can generate k8s manifests everywhere without additional external dependencies.
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In case of
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* java: Resources are included in the jar-file out of the box (see https://repo.prod.meissa.de/meissa/c4k-forgejo/src/branch/main/project.clj#L13).
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* js: With a slim macro call we inline resources to the resulting js file (see https://repo.prod.meissa.de/meissa/c4k-forgejo/src/branch/main/src/main/cljc/dda/c4k_forgejo/forgejo.cljc#L72-L74)
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* native: On native builds we also inline resources (see https://repo.prod.meissa.de/meissa/c4k-forgejo/src/branch/main/build.py#L126)
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#### Work on Structured Data Instead of Flat Templating
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To keep things simple, we also do templating. But we convert given k8s resources to structured data.
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This allows us to have more control and do unit tests:
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k8s-resource:
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```yaml
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apiVersion: traefik.containo.us/v1alpha1
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kind: Middleware
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metadata:
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name: ratelimit
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spec:
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rateLimit:
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average: AVG
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burst: BRS
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```
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Replace values:
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```clojure
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(defn-spec generate-rate-limit-middleware pred/map-or-seq?
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[config rate-limit-config?]
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(let [{:keys [max-rate max-concurrent-requests]} config]
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(->
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(yaml/load-as-edn "forgejo/middleware-ratelimit.yaml")
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(cm/replace-key-value :average max-rate)
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(cm/replace-key-value :burst max-concurrent-requests))))
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```
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Have a unit-test:
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```clojure
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(deftest should-generate-middleware-ratelimit
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(is (= {:apiVersion "traefik.containo.us/v1alpha1",
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:kind "Middleware",
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:metadata {:name "ratelimit"},
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:spec {:rateLimit {:average 10, :burst 5}}}
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(cut/generate-rate-limit-middleware {:max-rate 10, :max-concurrent-requests 5}))))
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```
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#### Validate Your Inputs
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Have you recognized the `defn-spec` macro above? We use allover validation, e.g.
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```clojure
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(def rate-limit-config? (s/keys :req-un [::max-rate
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::max-concurrent-requests]))
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(defn-spec generate-rate-limit-middleware pred/map-or-seq?
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[config rate-limit-config?]
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...)
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```
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#### Namespaces
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We support namespaces for ingress & postgres (monitoring lives in it's own namespace `monitoring`).
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```clojure
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(dda.c4k-common.namespace/generate {:namespace "myapp"})
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```
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yields:
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```clojure
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[{:apiVersion "v1"
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:kind "Namespace"
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:metadata {:name "myapp"}}]
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```
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which renders to:
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```yaml
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apiVersion: v1
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kind: Namespace
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metadata:
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name: myapp
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```
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#### Ingress
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In most cases we use `generate-ingress-and-cert` which generates an ingress in combination with letsencrypt cert for a named service.
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```clojure
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(dda.c4k-common.ingress/generate-ingress-and-cert
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{:fqdns ["test.jit.si"]
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:service-name "web"
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:service-port 80})
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```
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yields:
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```clojure
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[{:apiVersion "cert-manager.io/v1",
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:kind "Certificate",
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...
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:spec
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{:secretName "web",
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:commonName "test.jit.si",
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:duration "2160h",
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:renewBefore "720h",
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:dnsNames ["test.jit.si"],
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:issuerRef {:name "staging", :kind "ClusterIssuer"}}}
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{:apiVersion "networking.k8s.io/v1",
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:kind "Ingress",
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...
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:spec
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{:tls [{:hosts ["test.jit.si"], :secretName "web"}],
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:rules
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[{:host "test.jit.si",
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:http {:paths [{:path "/",
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:pathType "Prefix",
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:backend
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{:service {:name "web",
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:port {:number 80}}}}]}}]}}]
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```
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which renders to:
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```yaml
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apiVersion: cert-manager.io/v1
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kind: Certificate
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...
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spec:
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secretName: web
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commonName: test.jit.si
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duration: 2160h
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renewBefore: 720h
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dnsNames:
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- test.jit.si
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issuerRef:
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name: staging
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kind: ClusterIssuer
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---
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apiVersion: networking.k8s.io/v1
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kind: Ingress
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...
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spec:
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tls:
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- hosts:
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- test.jit.si
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secretName: web
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rules:
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- host: test.jit.si
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http:
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paths:
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- pathType: Prefix
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path: /
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backend:
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service:
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name: web
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port:
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number: 80
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```
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#### Postgres Database
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If your application needs a database, we often use postgres:
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```clojure
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(cut/generate-deployment {:postgres-image "postgres:16"})
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```
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yields:
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```clojure
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{:apiVersion "apps/v1",
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:kind "Deployment",
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...
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:spec
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{:selector {:matchLabels {:app "postgresql"}},
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:strategy {:type "Recreate"},
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:template
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{:metadata {:labels {:app "postgresql"}},
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:spec
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{:containers
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[{:image "postgres:16",
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:name "postgresql",
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:env
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[{:name "POSTGRES_USER", :valueFrom {:secretKeyRef {:name "postgres-secret", :key "postgres-user"}}}
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{:name "POSTGRES_PASSWORD", :valueFrom {:secretKeyRef {:name "postgres-secret", :key "postgres-password"}}}
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{:name "POSTGRES_DB", :valueFrom {:configMapKeyRef {:name "postgres-config", :key "postgres-db"}}}],
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:ports [{:containerPort 5432, :name "postgresql"}],
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:volumeMounts
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[...],
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:volumes
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[...]}}}}
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```
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which renders to:
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```yaml
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apiVersion: apps/v1
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kind: Deployment
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...
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spec:
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selector:
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matchLabels:
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app: postgresql
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strategy:
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type: Recreate
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template:
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metadata:
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labels:
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app: postgresql
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spec:
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containers:
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- image: postgres:16
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name: postgresql
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env:
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- name: POSTGRES_USER
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valueFrom:
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secretKeyRef:
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name: postgres-secret
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key: postgres-user
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- name: POSTGRES_PASSWORD
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valueFrom:
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secretKeyRef:
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name: postgres-secret
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key: postgres-password
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- name: POSTGRES_DB
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valueFrom:
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configMapKeyRef:
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name: postgres-config
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key: postgres-db
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ports:
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- containerPort: 5432
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name: postgresql
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volumeMounts:
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...
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volumes:
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...
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```
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We optimized our db installation to run between 2Gb anf 16Gb Ram usage.
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#### Monitoring With Grafana Cloud
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With minimal config of
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```clojure
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(def conf
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{:k3s-cluster-name "your-cluster-name"
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:k3s-cluster-stage :prod
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:grafana-cloud-url "your-url"})
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(def auth
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{:grafana-cloud-user "user"
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:grafana-cloud-password "password"})
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(monitoring/generate conf auth)
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```
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You can connect your application to grafana cloud.
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## Refactoring & Module Overview
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| Module | Version | [common load-as-edn][edn1] | [groups for webview][bgrp1] | [use common ingress][ing1] | [use common monitoring][mon1] | [validate examples][val1] | [ci with pyb][cipyb] | [inline-macro to load resources][macro] | [native build][native] | namespaces |
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| ------------- |---------|:--------------------------:|:---------------------------:|:--------------------------:|:-----------------------------:|:-------------------------:|:--------------------:|:---------------------------------------:|:----------------------:|:----------:|
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| c4k-keycloak | 0.2 | x | x | x | x | x | | | | |
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| c4k-taiga | 0.1 | x | x | x | x | x | x | x | x | |
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| c4k-nextcloud | 10.2 | x | x | x | x | x | x | x | x | x |
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| c4k-jitsi | 1.6 | x | x | x | x | x | x | x | | |
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| c4k-forgejo | 3.0 | x | x | x | x | x | x | x | x | |
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| c4k-shynet | 1.0 | | | | | | | | | |
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| c4k-website | 2.0 | x | x | x | x | x | x | x | x | |
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[edn1]: https://gitlab.com/domaindrivenarchitecture/c4k-website/-/merge_requests/1
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[ing1]: https://repo.prod.meissa.de/meissa/c4k-jitsi/commit/214aa41c28662fbf7a49998e17404e7ac9216430
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[bgrp1]: https://repo.prod.meissa.de/meissa/c4k-jitsi/commit/7ea442adaef727d5b48b242fd0baaaf51902d06e
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[mon1]: https://repo.prod.meissa.de/meissa/c4k-jitsi/commit/19e580188ea56ea26ff3a0bfb08ca428b881ad9a
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[val1]: https://repo.prod.meissa.de/meissa/c4k-jitsi/commit/5f08a108072569473463fb8f19150a12e564e54f
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[repo1]: https://repo.prod.meissa.de/meissa/c4k-forgejo/commit/e9ee6136f3347d5fccefa6b5b4a02d30c4dc42e1
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[cipyb]: https://gitlab.com/domaindrivenarchitecture/c4k-jitsi/-/merge_requests/1
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[macro]: https://repo.prod.meissa.de/meissa/c4k-jitsi/commit/61d05ceedb6dcbc6bb96b96fe6f03598e2878195
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[native]: https://repo.prod.meissa.de/meissa/c4k-forgejo/pulls/4/files
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## Development & Mirrors
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Development happens at: https://repo.prod.meissa.de/meissa/c4k-common
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Mirrors are:
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* https://gitlab.com/domaindrivenarchitecture/c4k-common (issues and PR)
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* https://github.com/DomainDrivenArchitecture/c4k-common
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For more details about our repository model see: https://repo.prod.meissa.de/meissa/federate-your-repos
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## License
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Copyright © 2022, 2023, 2024 meissa GmbH
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Licensed under the [Apache License, Version 2.0](LICENSE) (the "License")
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Pls. find licenses of our subcomponents [here](doc/SUBCOMPONENT_LICENSE)
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